Hydraulic lock valve with flow control

ABSTRACT

This hydraulic lock, for preventing escape of working fluid from a motor cylinder, is constructed so that working fluid flows freely to the cylinder for the working stroke of the cylinder, but reverse flow is prevented automatically unless a special flow control valve is operated. A valve assembly includes an actuator and two valve elements, one of which is a check valve that prevents outflow of working fluid from the cylinder; but the check valve permits free inflow to the cylinder. The other valve element has a reference orifice for flow control and a piston controlling the actuation. The second valve element maintains a flow control based on force applied to the actuator and on the pressure drop of working fluid flowing from the cylinder. In the preferred construction, the flow control valve closes against a seat carried by the check valve.

United States Patent Kowalski et al.

[ 1 Apr. 25, 1972 HYDRAULIC LOCK VALVE WITH Primary Examiner-Henry T. Klinltsiek FLOW CONTROL Attorney-Sandoe, l'lopgood 8L Calimafde [72] Inventors: Slawomlr Kowalski, Rockaway; Donald A. 57 ABSTRACT Worden, Pompton Plains, both of NJ. Thls hydraulic lock, for preventlng escape of work ng fluid [73] Asslgnee. Marotta Scientific Controls, Inc., Boonton, f a motor cyhnder constructed so that workmg fl id flows freely to the cylinder for the working stroke of the [22] Filed: Apr. 27, 1970 cylinder. but reverse flow is prevented automatically unless a speclal flow control valve is operated. A valve assembly in- PP 3 ,260 cludes an actuator and two valve elements, one of which is a check valve that prevents outflow of working fluid from the cylinder; but the check valve permits free inflow to the (gill 7 cylinder The other valve element has a reference orifice for 581 Field of Search ..l37/596, 596.l,599.2 and a The second valve element maintains a flow control based on force I applied to the actuator and on the pressure drop of working [56] Reerences Cited fluid flowing from thetcylinder. in the preferred construction, n- STATES P EN tlae ilowlcontroi valve closes against a seat carried by the e ec va ve. 3,244,196 4/1966 Replogle ..l37/599.2 X

11 Claims, 5 Drawing Figures 1 52 I I8 4. f 48 \\\\\\\/-38 45 i 1: 1.3 6 2 74 84 d .140 F 51 I0'4 L5 42/ 68' & 1

BACKGROUND AND SUMMARY OF THE INVENTION It has been common practice to have a valve in the liquid line to the cylinder of a hydraulic motor for shutting off back flow of working fluid from the motor, and such valves are referred to as hydraulic locks. This invention is. an improved hydraulic lock in an assembly with valvemeans for controlling the rate of flow of the working fluid from the motor cylinder, and for making the rate of flow proportional to the force applied by an actuator, when the working fluid in the motor is to be released.

The flow control valve for the liquid flowing from the cylinder has a reference orifice through which liquid flows with some pressure drop; and this drop, with certain pressurebalancing features, is used to make the rate of flow of the liquid through the valve assembly approximately proportional to the force that is applied to the flow control valve element by its actuator. The operation of the actuator can be either mechanical or manual.

In the preferred embodiment of the invention, a check valve element that serves as an automatic hydraulic lock slides in guides in a valve chamber and has a center opening through it with a valve seat around the edges of this opening. The flow control valve closes against this seat on the check valve. The control of fluid flow from the cylinder is effected by a piston connected with the flow control valve element and exposed on one side to hydraulic pressure on the downstream side of a reference orifice through which the fluid flows when the second valve element is in open position; and exposed on the other side to the upstream pressure ofthe fluid.

The actuator for operating the flow control valve is preferably a piston to which a controlled pressure is applied, and the rate of flow from the hydraulic motor cylinder is proportional to the force applied to this actuator piston. An electromagnetic actuator can be used in place of the cylinder and piston to obtain a flow proportional to the current applied to the electromagnet. If desired, provision can be made for operating the actuator manually.

BRIEF DESCRIPTION OF DRAWING In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

FIG. 1 is a diagrammatic view showing a hydraulic motor cylinder equipped with hydraulic locks made in accordance with this invention;

FIG. 2 is a greatly enlarged sectional view through one of the hydraulic lock assemblies of FIG. 1;

FIG. 3 is an end view, on a reduced scale, of the assembly shown in FIG. 1, the view being taken from the right-hand end of FIG. 2; and

FIGS. 4 and 5 are sectional views taken on the lines 4-4 and 5-5, respectively, of FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENT The combination shown in FIG. 1 includes a hydraulic motor cylinder which contains a piston 12 and a piston rod 14 that projects beyond the crank end of the cylinder 10. Tubing 16 communicates with a port opening into the head end of the cylinder 10 and there is a hydraulic lock 18 for regulating the flow of fluid through the tubing 16 and its associated port from the cylinder 10.

The cylinder 10 has tubing 16 communicating with a port at the crank end of the cylinder and has a hydraulic lock 18' for controlling the flow of working fluid from the cylinder through the tubing 16 and its associated port. The hydraulic locks 18 and 18 are connected by other tubing 20 and 20', respectively, to a slide valve assembly 22. This slide valve assembly 22 is of conventional construction and is representative of valve means for connecting the hydraulic locks 18 and 18 with fluid supply and exhaust ports.

When the slide valve assembly 22 has its pistons 24 in the full+line positions shown in FIG. 1, working fluid under pressure from a supply line 26 can pass through a cylinder 28 of the slide valve and through the'tubing 20' to the hydraulic lock 18. The other tubing 20 fromthe hydraulic lock 18 communicates through the slide valve cylinder 28 withian exhaust line 30.

When the pistons 24, both of which are rigidly connected with a piston rod 32, are movedintothe positions shown in broken lines in FIG. 1, the situation is reversed. The hydraulic lock 18' is put in communication with an exhaust port 34 and the hydraulic lock 18 is put into communication with the working fluid supply line 26.

FIG. 2 shows the construction of the hydraulic lock 18 and it will be understood that the construction of the hydraulic lock 18' is similar. The hydraulic lock 18 includes a housing 38 having a first port 40 which communicates with the tubing 20 and a second port 42 which communicates with the other tubing 16. Both of these ports open into a valve chamber 44. The valve chamber 44 is generally cylindrical, but stepped to included an upper end cylinder 46 of smaller diameter than the other part of the valve chamber 44; and to include also a lower portion 56. This cylinder 46 serves as a guide fora piston 48 which is part of the actuator for the valve assembly. Working fluid for the actuator is supplied to the cylinder 46 through an upper port 50 to which a supply and exhaust line 52 is connected. For automatic release of the hydraulic lock 18 by working fluid supplied to the hydraulic lock 18' (FIG. 1), at the other end of the cylinder 10, the line 52 can be connected to the tubing 20. For similar release of the hydraulic lock 18 by fluid supplied to the hydraulic lock 18. another line 52 can be connected from the actuator port of hydraulic lock 18' to the tubing 20, as shown in FIG. I.

The valve chamber 44 has a lower portion 56 of increased diameter as compared with the portion of the chamber 44 above it. There isa threaded counterbore 60 at the bottom end of the valve chamber44; and a-bushing 62 screws into the threaded counterbore 60.

There are two valve elements in the valve chamber 44. One of these is ach'eck valve element having its upper portion slideable in the valve chamber 44 as a guide; the contact of the valve element'64 with the cylindrical side wall of the valve chamber 44 being located above the first port 40. The lower end of the check valve element 64 has a cylindrical surface 66 whichslides in a bore in aguide element 68 that fits into the larger diameter lower portion 56 of the valve chamber. The guide element 68 bottoms against the bushing 62 and is sealed with an-O-ring70. This guide element 68 is adjustable within limits by screwing the bushing 62 one way or another in the threads of the counterbore 60.

The check valve element 64, when in closed position, contacts with a seat 74 provided by a shoulder 76 at the region where the diameter of the valve chamber 44 changes to the larger diameter of the lower portion 56 of the valve chamber.

The check valve element 64 is hollow and it has ports 80 through which the valve chamber 44 communicates with the interior of the check valve element 64.

Near the lower end of the check valve element 64 it has a valve seat 82 and there is a flow control valve element 84 which seats against the seat 82 on the check valve element 64. The flow control valve element 84 is urged against the seat 82 by a helical compression spring 86 that is held compressed by a bottom of a socket 88 at the lower end of the guideelement 68.

The flow control valve element 84 has a flange or piston 90 supply working fluid to the clearance between the flow control valve element 84 and the seat 82 when the flow control valv element 84 is in open position.

There is a sealing ring 98 in a guide 100 concentric with the cylinder 92. The flow control valve element 84 moves in the guide 100 at its lower end and had its upper end held in a socket 102 in the piston 48. The sealing ring 98 prevents pressure under the piston 90 from reaching the lower end of the flow control valve element 84 and from getting into the hollow portion of the valve element 84 which houses the spring 86 This hollow portion communicates with the interior of the check valve element 64 through an axial passage 104 and radial passages 106.

The bushing 62 is held in any adjusted position by a locking slug 110 clamping against the threads of the bushing by a set screw 112 threaded into an opening in the side wall of the housing 38. Adjustment of the bushing 62 determines in effect the size of the reference orifice 96 by moving it with respect to the end face of the element 66. Reducing the cross section of the orifice 96 makes the apparatus require higher pressure in the actuator cylinder 46 to obtain the flow through the unit.

The operation of the valve assembly shown in FIG. 2 is as follows:

the parts occupy the positions shown in FIG. 2 when there is pressure in the cylinder and in the tubing 16 but no pressure or lesser pressure in the tubing 20 and port 40, and any pressure at the port 50 of the actuator is insufficient to open the flow control valve 84. Working fluid pressure is the same both above and below the piston 90 because the flow control valve element 84 is closed against the seat 82 and there is no flow of fluid or pressure drop on either side of the piston 90. This piston 90 is counterbalanced for pressure in the cylinder 92 since the inner diameter of the piston 90 is equal to the effective diameter of the valve seat 82.

The check valve element 64 is exposed to the same pressure as that against the upper face of the piston 90 and the check valve element 84 is also exposed to the force of the compression spring 86'which holds the flow control valve element 84 against the seat 82 so long as pressure against the upper face of the actuator piston 48 is insufficient to open the flow control valve 84. Thus with the .parts in the positions shown in FIG. 2, no pressure can escape through the port 42 from the hydraulic motor cylinder.

The flow control valve element 84 is balanced as to pressure from the ports 40 and 42 since the seal 98 is of the same diameter as the effective diameter of the seat 82.

Whenever the slide valve 22 (FIG. 1) is operated to put the tubing 20 in communication with the working fluid supply line 26, then the pressure in the port 40 and valve chamber 44 of F [0.2 causes the valve element 64 to move downward in FIG. 2 and away from the seat 74. This movement of the check valve element 64 moves the flow control valve element 84 with it and compresses the spring 86.

Working fluid flows freely past the check valve element 64 and through the port 42 to the hydraulic cylinder.

When working fluid is to be exhausted from the hydraulic motor, pressure is applied through the port 50 to the actuator piston 48 with sufficient pressure to move the piston 48 downward against the force of the spring 86. This moves the flow control valve element 84 away from its seat 82 and working fluid immediately flows from the. hydraulic cylinder through the port 42 and through the ports 96 and through the clearance between the flow control valve element 84 and its seat 82.

This flow of fluid causes a pressure difference on opposite sides of the piston 90. The pressure difference is maintained as long as the fluid flow continues and is accentuated by the fact that the fluid flowing past the open valve element must pass through the limited areas of the reference orifices 96.

The pressure inv the lower part of the cylinder 92 under the piston 90 does not drop substantially when the flow control valve element 84 opens because there is no flow of fluid from the cylinder 92 below the piston and the orifices 94 through which the cylinder below the piston communicates with the port 42, communicate with the port upstream from the reference orifices 96.

This resulting pressure drop that accompanies the flow of fluid when the flow control valve element 84 moves into open position produces a differential pressure across the piston 90. This pressure is substantially proportional to the rate of flow of the working fluid because the excess pressure under the piston 90 moves the flow control valve 84 toward closed position. This movement continues until the reduction in the rate of flow reduces the pressure differential across the piston 90 to a value that balances the net force exerted on the flow control valve element 84 by the combined action of the spring 86 and the fluid pressure against the upper end of the actuator piston 48.

Thus the rate of flow of working fluid from the hydraulic motor is proportional to the force exerted through the port 50 against the actuator piston 48. If a slow motion of the hydraulic motor is desired, a reduced pressure is exerted against the upper end of the piston 48; and if faster movement of the hydraulic motor is desired, the pressure on the piston 48 is increased The fluid pressure to the actuator piston 48 can be controlled by placing pressure regulators 97 in the fluid lines 52 and 52' or by having these fluid lines supplied with working fluid independently of the fluid supply from the line 26, or by using a proportional flow control valve in place of the slide valve 28. v

The check valve 64 is held closed during this flow of working fluid from the port 42 to the port 40 because the lower end of the check valve 64 is subjected to higher pressure than the upper end; the pressure difference being the pressure drop across the valve seat 82. Thus the check valve 64 has no effect upon the flow control when working fluid is moving from the port 42 toward the port 40 during exhaust of fluid from the head end of the hydraulic motor. The check valve element 64 is open only when liquid is flowing from the port 40 toward the port 42; and the flow control valve element 84 is open only when the flow is in the opposite direction.

FIG. 3 shows the port 40 which is circular where it opens through the outside surface of the housing 38. The inner end of the port 40, which communicates with the valve chamber 44, is preferably of elongated cross section as indicated by the reference characterl20, to reduce resistance of flow between the port 40 and the valve chamber.

The preferred embodiment of the invention has been illustrated and described, but changes and modifications can be made and some features can be used in different combinations without departing from the invention as defined in the claims.

What is claimed is:

l. A valve assembly for a hydraulic motor including a housing enclosing a valve chamber having a first port for flow of working fluid to and from the valve chamber, and a second port for connection with a hydraulic motor cylinder, first and second valve elements in the chamber, a different seat against which each of the valve elements closes, reference orifice means through which working fluid flows from this second port to the, valve seat for the first valve element, the first valve element having one surface exposed to the pressure at the second port and another surface exposed to the pressure downstream of said reference orifice means whereby the force to hold the first valve element open is proportional to the rate of flow of working fluid past said first valve element, an actuator connected with the first valve element for moving it into open position, means in the housing and operably connected with the first valve element for biasing the first valve element toward closed position, the second valve element being a check valve that is closed by flow of fluid through the valve chamber from the second port to the first port, said second valve element being movable into open position for free flow of working fluid from the first port through the valve chamber to the second port independently of the reference orifice means.

2. The valve assembly described in claim 1 characterized by guide means in which the first valve element is held, said first valve element, when in closed position, being pressurebalanced as to pressure in the first port, and also pressurebalanced as to pressure in the second port, whereby the actuator force to move the first valve element into open position is independent of the pressure in the valve chamber.

3. The valve assembly described in claim 1 characterized by the valve elements being concentric and both of the valve elements being oriented to close against pressure of the first port, the seat for the first valve element being carried by the second valve element, and the second valve element being held in closed position by pressure of the first valve element against its seat.

4. The valve assembly described in claim 3 characterized by theactuator being a piston that slides in a cylinder guide at one end of the valve chamber and that moves the first valve element into open position, and the means for biasing the first valve element toward closed position being a spring that acts against the force exerted by the actuator.

5. The valve assembly described in claim 3 characterized by the second valve element being unbalanced as to pressure in the first port with an area against which the first port pressure acts to move the second valve element into position when the pressure applied to the first port exerts a force against the second valve element in excess of that exerted on the second valve element from the pressure in the second port and the means biasing the first valve element toward closed position.

6. The valve assembly described in claim 1 characterized by the first valve element having a flange portion that slides in a part of the valve chamber as a piston, said part of the valve chamber extending toward a location adjacent to the plane of the valve seat of the first valve element and being closed at that end when the first valve element is in contact with its seat,

but having the reference orifice means opening through the side of said part of the valve chamber that extends toward said location for producing a pressure drop when the first valve element is open and working fluid is flowing through the reference orifice means, the other end of said part of the valve chamber in which the flange portion slides being open to the pressure in the second port upstream of the reference orifice means.

7. The valve assembly described in claim 6 characterized by the effective transverse areas of the flange portion of the first valve element being substantially equal on both sides so that the flange portion is pressure-balanced as to the pressure in the second port when the first valve element is in closed position and there is no flow of working fluid through the reference orifice means.

8. The valve assembly described in claim 6 characterized by the seat for the first valve element being carried by the second valve element, and part of the second valve element sliding in the samepart of the valve chamber as the flange portion of the first valve element and comprising an end wall that closes the said end of the part of the valve chamber in which the flange portion of the first valve element slides.

9. The valve assembly described in claim 1 characterized by a fluid passage communicating with the first port, for selectively supplying working fluid under pressure to said port and opening the port for exhaust of working fluid therefrom.

10. The valve assembly described in claim 1 characterized by means for adjusting the cross section area of the reference orifice means to change the flow for a given force that holds the first valve element open.

11. The valve assembly described in claim 10 characterized by the adjusting means including a part operable from outside of the housing. 

1. A valve assembly for a hydraulic motor including a housing enclosing a valve chamber having a first port for flow of working fluid to and from the valve chamber, and a second port for connection with a hydraulic motor cylinder, first and second valve elements in the chamber, a different seat against which each of the valve elements closes, reference orifice means through which working fluid flows from this second port to the valve seat for the first valve element, the first valve element having one surface exposed to the pressure at the second port and another surface exposed to the pressure downstream of said reference orifice means whereby the force to hold the first valve element open is proportional to the rate of flow of working fluid past said first valve element, an actuator connected with the first valve element for moving it into open position, means in the housing and operably connected with the first valve element for biasing the first valve element toward closed position, the second valve element being a check valve that is closed by flow of fluid through the valve chamber from the second port to the first port, said second valve element being movable into open position for free flow of working fluid from the first port through the valve chamber to the second port independently of the reference orifice means.
 2. The valve assembly described in claim 1 characterized by guide means in which the first valve element is held, said first valve element, when in closed position, being pressure-balanced as to pressure in the first port, and also pressure-balanced as to pressure in the second port, whereby the actuator force to move the first valve element into open position is independent of the pressure in the valve chamber.
 3. The valve assembly described in claim 1 characterized by the valve elements being concentric and both of the valve elements being oriented to close against pressure of the first port, the seat for the first valve element being carried by the second valve element, and the second valve element being held in closed position by pressure of the first valve element against its seat.
 4. The valve assembly described in claim 3 characterized by the actuator being a piston that slides in a cylinder guide at one end of the valve chamber and that moves the first valve element into open position, and the means for biasing the first valve element toward closed position being a spring that acts against the force exerted by the actuator.
 5. The valve assembly described in claim 3 characterized by the second valve element being unbalanced as to pressure in the first port with an area against which the first port pressure acts to move the second valve element into position when the pressure applied to the first port exerts a force against the second valve element in excess of that exerted on the second valve element from the pressure in the second port and the means biasing the first valve element toward closed position.
 6. The valve assembly described in claim 1 characterized by the first valve element having a flange portion that slides in a part of the valve chamber as a piston, said part of the valve chamber extending toward a location adjacent to the plane of the valve seat of the first valve element and being closed at that end when the first valve element is in contact with its seat, but having the reference orifice means opening through the side of said part of the valve chamber that extends toward said location for producing a pressure drop when the first valve element is open and working fluid is flowing through the reference orifice means, the other end of said part of the valve chamber in whiCh the flange portion slides being open to the pressure in the second port upstream of the reference orifice means.
 7. The valve assembly described in claim 6 characterized by the effective transverse areas of the flange portion of the first valve element being substantially equal on both sides so that the flange portion is pressure-balanced as to the pressure in the second port when the first valve element is in closed position and there is no flow of working fluid through the reference orifice means.
 8. The valve assembly described in claim 6 characterized by the seat for the first valve element being carried by the second valve element, and part of the second valve element sliding in the samepart of the valve chamber as the flange portion of the first valve element and comprising an end wall that closes the said end of the part of the valve chamber in which the flange portion of the first valve element slides.
 9. The valve assembly described in claim 1 characterized by a fluid passage communicating with the first port, for selectively supplying working fluid under pressure to said port and opening the port for exhaust of working fluid therefrom.
 10. The valve assembly described in claim 1 characterized by means for adjusting the cross section area of the reference orifice means to change the flow for a given force that holds the first valve element open.
 11. The valve assembly described in claim 10 characterized by the adjusting means including a part operable from outside of the housing. 